Explain how the calculated molarity of the potassium permanganate would be affected by each of the following experimental errors. In each case, you must also state if the calculated molarity is higher or lower than the actual morality.
a) Some sodium oxalate was spilled after it had been weighed out on the analytical balance.
b) Prior to its use, the pipet has not been rinsed with the standard sodium oxalate solution.
c) The Erlenmeyer flask was rinsed with the sodium oxalate instead of deionized water before the 25.00 mL solution was measured into it.
d) The endpoints were repeatedly overshot.
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a) If some sodium oxalate is spilled after being weighed out, it means that less sodium oxalate will be available for the reaction. Since the molarity of potassium permanganate is calculated based on the stoichiometry of the reaction, a decrease in the amount of sodium oxalate will lead to a lower calculated molarity of potassium permanganate. Therefore, the calculated molarity will be lower than the actual molarity.
b) If the pipet has not been rinsed with the standard sodium oxalate solution before use, there might be residual solution left in the pipet from previous experiments. This will introduce additional sodium oxalate into the flask, causing the reaction to proceed with a higher amount of sodium oxalate. As a result, the calculated molarity of potassium permanganate will be higher than the actual molarity.
c) If the Erlenmeyer flask is rinsed with the sodium oxalate solution instead of deionized water, it means that some sodium oxalate will be introduced into the flask before the solution is measured into it. This will increase the amount of sodium oxalate in the reaction, leading to a higher calculated molarity of potassium permanganate.
d) When the endpoints are repeatedly overshot, it means that the volume of potassium permanganate solution needed to reach the endpoint is consistently higher than expected. This could be due to an issue with the titration technique, such as adding the titrant too quickly or not accurately observing the color change. Overshooting the endpoint will result in a higher volume of potassium permanganate used, which will lead to a higher calculated molarity than the actual molarity.